This Week in History


Tragedy in the Atlantic

For the week of Monday, September 19, 2016

On September 24, 1943, one of the most dramatic convoy battles of the Second World War ended. The four day battle saw heavy Allied losses including the Canadian destroyer HMCS St. Croix.

HMCS St. Croix at sea
© Canadian War Museum

The Battle of the Atlantic was the longest battle of the Second World War. Fought over the North Atlantic’s vital shipping routes, it cost the lives of 4,600 Canadians. German U-boats, organized in “wolf packs,” initially inflicted heavy losses on Allied shipping between Canada, the United States, and Britian. In 1943, the German navy deployed a new weapon that the Allies called the German Naval Acoustic Torpedo (GNAT), which used the sound of a ship’s propeller to home in on its target.

On September 20, five additional escort ships from Halifax, N.S., including HMCS St. Croix, joined a combined convoy of 63 Allied ships. That evening, the convoy was attacked by a wolf pack armed with the new GNAT. The U-boats targeted the convoy’s escort and quickly sank the frigate HMS Lagan. St. Croix was struck by three torpedoes early on in the battle and went down. HMS Polyanthus was sent to rescue the survivors, but was struck by a torpedo before reaching them. Thirteen hours after St. Croix sank; HMS Itchen was able to pick up 81 survivors. However, the following day Itchen was also torpedoed and only three survivors were rescued, one of whom was from St. Croix. The battle finally ended on September 24, when heavy fog cleared allowing aircraft from Newfoundland to drive off the U-boats.

St. Croix’s crew were volunteers from across Canada and their loss was felt nation-wide
© Canadian War Museum

As a counter-measure to the GNAT, the Allies developed “Canadian Anti-Acoustic Torpedo (CAT) Gear,” a device towed behind a ship that mimicked the sound of the propeller and lured torpedoes away from the ship, rendering the new German weapon far less effective.

For their vital importance during the Second World War, the Battle of the Atlantic and the Role of the Canadian Merchant Navy During the Second World War were designated national historic events.

For more stories about the Battle of the Atlantic, read Canadian Made Commander-in-Chief, Organizer of the North Atlantic Convoy System Born!, Battle of the Atlantic - War on the Homefront, and Courage, fortitude, and determination: Canada’s Merchant Navy in the This Week in History archives.

Follow us on Twitter @ParksCanada. Find out more about the Historic Sites and Monuments Board of Canada.

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